Spy-checking

From TF2 Wiki

Because of the Spy's ability to cloak or disguise as a character of the opposite team, it is useful to often check for the telltale signs of an enemy Spy in order to prevent them from backstabbing team-mates or sapping buildings.

Signs that indicate an enemy Spy

• A teammate stops when bumping into him (true teammates pass through you).
• A Medic without an ÜberCharge meter.
• A Scout moving at the Spy movement speed.
• Having your own name, or seeing your name yell a voice command that you didn't use.
• Having the name of somebody known to be elsewhere or dead.
• Having a name that does not correspond with the player's current class on the scoreboard. This happens when a Spy disguises himself as a class not currently on the team. It can also happen if the person has changed class while the Spy was disguised.
• The most common method used for Spy-checking is a Pyro puffing his teammates with his flamethrower. If the teammate does not ignite, he is not a Spy. If he does, take him down.
• A teammate standing on a friendly structure that he didn't build. Only engineers can only stand on friendly structures, and only ones belonging to them.
• While cloaked, briefly glowing his team color when bumped or shot.
• Obstructing friendly contact projectiles such as Rockets and Pipe bombs. Such weapons will usually shoot straight through team-mates.
• Placing Sappers on friendly buildings.
• A friendly Pyro on fire (they are normally flame-resistant).
• Any player that is on fire will glow their true team colour.
• Whenever he dons a disguise, an enemy Spy is given a fake and randomized 50%-80% health level that shows up to the other team. The spy can remove this clue by tricking an opposing medic into healing him.
• The Spy can never feign a health level less than 50%. Neither dispensers nor health packs can increase his apparent health. A spy can only consume health powerups if he is truly below 100% health, so a player who appears damaged but runs over health without picking it up is likely a spy.
• Being healed by an enemy dispenser while cloaked (healing "ribbons" are still visible). Cloaked friendly spies may also be revealed this way.
• While uncloaking, the spy is briefly coloured in his own team colour until he's uncloaking is complete.
• This tactic requires a blutsauger: If you see someone who you suspect is a spy, fire a single needle at him and look at your health. If you see a green +3 rising from it, that person is a spy and should be blutsaugered/bonesawed to death.
• A friendly player on a control point or neat a payload cart who does not seem to be capping the point or pushing the cart.
• Sometimes a teammate that deliberately avoids walking through you in tight corridors is a careful Spy.

Signs that indicate that a teammate is not a Spy

• Able to be passed through, as opposed to stopped short.
• Shooting a weapon.
• Holding any tool/weapon other than the primary weapon (the disguised Spy can only display that class's primary weapon).
• A Scout moving at the normal Scout movement speed.
• A Scout double-jumping.
• A Medic with an Ubercharge meter.
• Being surrounded by teleport particles of your team's color.
• Entering the resupply area.
• Reloading.
• Taunting.
• Carrying the enemy Intelligence.
• A Spy indicated as wearing a disguise.
• A fully cloaked Spy that is visible to you with a wavering outline.
• A Sniper with his Rifle to his eye (instead of holding it idly).
• A Heavy spinning his Minigun.
• A friendly player who is using their microphone: A symbol appears over the player's head. In servers with sv_alltalk enabled, the symbol is tinted red or blue according to the player's true team allegiance.
• Holding a unlockable weapon (e.g Blutsauger or Backburner).

Proving that you are not a Spy

This is short set of ways to stop your teammates from needlessly spy checking you.

• Switch to a different weapon (Spies in disguise only appear to be using the class's primary weapon).
• Shoot your weapon (a spy reveals himself by attacking).
• Agree to a sequence of moves in set up time (e.g. crouching twice).
• Taunt.
• Use your voice chat to say that you are not a Spy (e.g. "Just me").
• Walk through a teammate.